


The Ashen Demon of Britannia

by takerur



Category: Code Geass, Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: F/M, Hurt No Comfort, Knight of the Rounds Byleth, Past Relationship(s), Professor Byleth, Self-Harm, Teacher Byleth
Language: English
Status: Completed
Published: 2020-06-09
Updated: 2020-06-09
Packaged: 2021-03-04 07:00:49
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 13,809
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24629698
Author URL: https://archiveofourown.org/users/takerur/pseuds/takerur
Summary: Byleth puts three emperors on the Britannian throne while searching for his immortal lover. What's another Emperor… or two?
Relationships: Byleth/C.C., C.C./Lelouch Lamperouge | Lelouch vi Britannia, My Unit | Byleth/Sothis
Comments: 3
Kudos: 17





	The Ashen Demon of Britannia

_The Ashen Demon of Britannia_

* * *

Charles vi Britannia, 9th prince of Britannia, 21st to the throne, freshly 18 years old, stood impassively as an older cadet screamed profanities in his ear. Apparently his cover was too flat. It made him laugh inwardly as he remarked on the irony of a plebian screaming and ordering a royal prince. His heritage made him above these commoners. Even if they were nobles, it didn't really matter.

But Victoria Military Institute didn't care about nobility. Not _really._ VMI was an academy that prided itself on allowing skilled commoners to become officer candidates. After commissioning, their graduates showed tremendous success. That did not mean, however, nobles that graduated from other academies enjoyed commoners getting ranks that surpassed theirs. Their active sabotage was only curbed by the numerous VMI alumni that held high ranks, such as four Knights of Round. Its 500-year history and tradition were one of the only reasons there were VMI alumni in high positions. However, they all earned it.

In the academy, nobles were not given preferential treatment, nor was it tolerated. It was an academy that was run mainly by its cadets. Through this system, the camaraderie and networking were undeniably the best. In many ways, it was looked down upon as the "academy for commoners" in the military, but their graduates were undeniably as good or better than many of the nobles that graduated from other academies. Of course, they were not always promoted accordingly to their talents due to sabotaging by nobles. Even in the military, politics went into play.

The only reason he was here was that he knew as the 9th prince and not exactly close to the line of succession, his father was already making plans to have him engaged to a walrus of a woman who was the daughter of a Marques. He chose to commission as an officer before his father could have the chance to order him to get married.

He got down on his knees and into a push-up position. He wasn't a fighter, but his big frame said otherwise to the older cadets. After cranking out ten push-ups, he hurriedly got back onto his feet as the cadet kept screaming him to get up. He was a strategist and wasn't planning to make a career out of the military as many of his brothers were (or planned to). He would form a royal guard capable of defending him and— dare he say it aloud— become the next emperor.

.

The ninth prince of Britannia hated his father. With his so called "neutrality" within the game for the throne between his half brothers and sisters, he caused the death of his mother as well as making his brother never being able to age beyond the age of nine. In essence, he was paranoid that his children will try to kill him in order to take the throne. He wanted to become immortal, but he will _never_ know the truth of achieving immortality.

Charles and Victor made a promise to never lie to each other, as well as to get revenge at the current emperor for playing with their lives. After he ascends to the throne, he would make the Holy Empire more great and powerful than it has ever been. His older brother may have been a great emperor, but his condition made it impossible. Not to mention he was 'killed' by an assassin already.

He knew he was going to have to work hard in order to gain subordinates. His physical capabilities were shoddy at best but in actual battle as an officer, it would not be his physical strength that would win battles, but rather his mental fortitude.

.

Charles didn't care for many of the professors here. They were useful, but they weren't extraordinary. His first week of actual officer school after summer training (summer hell) was most easily summarized as boring.

He wanted to take more extracurricular subjects that would help him grow his mind rather than his almost nonexistent muscles. He gave a glance at the twenty or so pamphlets sprawled in front of him. The biggest part of VMI was their extracurricular clubs. It was a place where people gained friends and allies.

But all he needed were subordinates.

He looked at the pamphlets he was given by many upperclassmen and shifted through the pile.

Fencing— he didn't care for exercise

Football— even worse than fencing, even with the club members being very adamant about having him because he was tall.

Math club— his mathematics grades were excellent but didn't care too much about having mathematicians as allies. He threw the pamphlet to the 'maybe' pile

Business— he supposed financial backing would be beneficial, but Earl Callahan's son seemed to be a member already, going by him looming over and glaring at him as the business club publicity representative handed him a flyer. He would rather jump from a 10 story building than be in the same classroom as that _heathen._

He looked impassively at the Strategy Club pamphlet. It looked interesting. He would see how intelligent these club members were and if he even needed such a club.

.

There were a few dozen freshly admitted cadets that were interested in the Strategy club, but it seemed that there were only a dozen or so upperclassmen. The advisor was not yet in the classroom and the upperclassmen just seemed to be waiting patiently.

The doors to the classroom soon opened, revealing a young lime-green haired man dressed in a dark uniform accented with black shoulder plates. His sleeves were open, revealing glistening metal gauntlets protecting his arms. On his waist was a white sword that wasn't made out of metal. It looked… somewhat organic.

But overall, he looked ready for a battle.

"Good afternoon cadets. I am Byleth Eisner." His eyes didn't show any emotions he motioned for one of the upperclassmen to come closer to him. The upperclassman walked up, seemingly knowing what to expect. "First, I am going to give all of you an exam to see if you have the ability to master strategy. Strategy can be learned but cannot be developed further than your capabilities. If you have the ability to master it, I promise that you will go above and beyond what you could have ever imagined in your military career."

He passed a small stack of papers to the waiting upperclassman who handed out the paper tests to everyone, including the upperclassmen, and ended by grabbing one for himself and taking his previous seat.

"You may begin."

Charles looked at the test in front of him. It was only three questions, ones that had too many variables that were unpredictable.

 _The tide of a war is determined by strategy, not tactics._ The test was very adamant about that.

Maybe this club would be useful after all.

Also, Eisner—the name was somewhat familiar.

He would have to write some letters after this exam.

.

Charles zi Britannia crumpled up the letter in his hand while pushing himself more into the corner of the pew in the back of the White Chapel. He got the letters he wanted, but also an extra letter with news that made his eyes burn with rage.

It's quite hilarious really. Between assassinations between the royal family, the war between Britannia and the EU, and civil uprisings in Areas, Charles couldn't have picked a better time to join the military.

Really.

His four-year education plan to stay as far away from Pendragon cames to an abrupt halt as he is _drafted_ within four months of starting school to quell the civil uprising in Area 3. Drafting offices wouldn't make such an oversight to draft a Prince of Britannia. However, there was the Emperor's own signature and seal on the bottom. Charles knew without a doubt that his oldest brother Edmund su Britannia—Crown Prince of Britannia who was quite sure that he would inherit the throne—managed to convince his father that Charles would need to prove himself as a capable officer for the Empire.

Oh, nevermind that Edmund _never_ lifted anything heavier than a book in his life. This was his sadistic way of getting rid of him.

Charles trembled. In fear or anger—he wasn't very sure. He didn't apply to VMI to enlist as a soldier. He didn't want to head into _assured death_ due to his half-brother's schemes. He had enough of those already.

He was glad that he was in the chapel where no one bothered him. He wasn't particularly religious— his understanding of the 'God' people worship was already crushed as he learned how pathetic the God of this world was as he and his older brother gained their powers.

He looked up and almost jumped.

The professor of his Strategy Club—Professor Eisner, was sitting in a pew three rows in front of him.

Even with all the rage burning inside him, Charles couldn't suppress the urge to prod at the mysterious professor's mind.

"I didn't take you as a religious person, Professor." He didn't know if talking to the Professor would result in much, but if something bad happened, then he would use his Geass.

The professor chuckled but didn't turn around.

"Not exactly. Not to this religion, at least."

"Oh? It is rather strange of you to be in a chapel then."

"My lover liked chapels."

Charles rose one of his brows. He didn't think that such an emotionless professor would have a lover. "Do you go visit her often?" He knew the professor lived on the campus housing for the professors, ones that the non-married professors live in.

Professor Eisner shook his head.

"No, I haven't been able to see her in a while."

"I see." So, it didn't seem like she was exactly dead. It was ambiguous as the professor used past tense.

"Having troubles at home, Charles? Ah, is it okay to call you by that?"

Charles narrowed his eyes at the professor, who still haven't turned around to face him.

"I thought you would mind decorum more as a professor. I do not mind." Charles narrowed his eyes.

He _did_ mind, but from his letters, the professor was pretty well connected.

"And why do you ask, professor? You do realize it means you are meddling with the matters of the royal family?"

"I'm not trying to curry your favor, Charles. I don't care for any fancy titles, but I can be very…" The professor was searching for a word. " _Helpful_."

Charles snorted. There was no human who does things for free. "In what ways, professor?"

Professor Eisner finally turned around with a small smirk on his face.

"Power."

.

Charles knew the history of all the past Britannian emperors, and as he thought, the professor was from _the_ Eisner family that was famous (or infamous) for being instrumental in putting three Britannian emperors onto the throne. He sent a request to historians at Pendragon to get the records on his Professor.

Professor Eisner was the heir to a Dukedom. His father, Jeralt Eisner VI, was the Duke of Fodlan, a large island in Euro Britannia, and had a claim to the surrounding areas.

Before Britannia even had a footing in Europea United, in A.T.B. 1702, Jeralt Eisner II invaded Fodlan Island and pushed onward to surrounding land with a hundred men and conquered a sizable chunk of territory for Britannia. This was the same man who put the 81st Emperor Andreas nel Britannia to the throne. He was given Fodlan Island and the surrounding lands as a reward. There was a small excerpt about possible sister wife he had, who soon disappeared after the conquest.

Over a hundred years later, Byleth VIII was given the title of Marquess of Fodlan after helping the 85th Empress Othelia li Britannia to the throne.

Professor Eisner's great grandfather, Byleth Eisner IX, was elevated to a Duke for helping raise the 93rd Britannian Emperor Alec la Britannia to the throne.

In the previous eras, family history was not very publicized or recorded well, but all men from the Eisner family were either named Jeralt or Byleth. Interestingly, there was only one mention of a possible wife. Or a sister wife. There were so many gaps in the Eisner family history, which made Charles scrutinize the information he had.

It was strange. Most nobles were so proud of their lineage and noble status that they kept careful and detailed accounts of their family history. Moreover, nobles all appeared in court and public a few years before reaching adulthood, but the Eisner family had been missing from court for over 70 years.

He knew that his brothers that wanted the throne would have approached Professor Eisner for help. For this man to approach _him_ and offer to give him the throne…

 _And he didn't even have to use his Geass,_ Charles smirked.

.

Charles panted quietly behind an overturned tank. He held the assault rifle that he scavenged off a dead Britannian soldier. The insurgents were getting closer, but he couldn't die here.

_-"Charles?"_

He heard a voice coming out of a radio. He couldn't know if this person was an enemy who somehow found the channel in the communicator near him. He wouldn't respond yet.

_"This is Eisner. Commencing plan Alpha-November-Lima-008. Hold your ground and disengage comms. Over."_

To a random passerby or any other Britannian soldier, this would sound like a gibberish of Military Phonetic Alphabet. However, this was a code between him and the professor, signaling an extraction and his ETA.

"Roger. Victory-02. Over."Charles finally responded and snapped the radio in half. He definitely grew stronger but didn't dwell on it as there were more important matters at hand.

Professor Eisner would get here in eight minutes. He just needed to survive that long.

.

"Here's a Brit!"

Charles heard a yell coming from his right. He dodged the stray bullet coming at him and quickly shot the Three who gave away his position.

 _Shit. Shit._ Charles whispered to himself. He hadn't look at the watch. If he did, eight minutes would be even more excruciating.

He heard some more hurried footsteps.

"Put your weapon down and hands up you Britannian fucker!" He could tell from the footsteps that there were four men, about 30 meters away.

Charles didn't move from his spot, but he saw a grenade pin glistening in the darkness by fire attached to a dead Britannian's tactical vest to his left, six meters away. He couldn't run to grab it as it would leave him exposed to gunfire. However, if the Threes chose to come close to him, he could try to shoot at the grenade to cause it to explode. That, however, would be the last resort.

Where is fuck is the Professor? Ugh, if only he had his brother's Code at this moment. His brother would no doubt lecture him about using such foul language as a Britannian Prince, but Victor didn't have to worry about _dying_ in the middle of a battlefield.

He could hear a few bullets hitting the tank he was hiding behind, the Threes trying to make him come out of his hiding spot.

They were stupid to just waste their bullets, but they outnumbered him. He could hear them not-so-quietly yelling to split into two groups, no doubt planning to corner him on both sides.

The grenade it is, then.

He aimed toward the grenade and put his finger on the trigger.

And then something black dropped down.

"Fuck!" Charles cried out as his trigger finger twitched. He saw that it was his professor and sighed. "I almost shot you! You better be thankful that I'm not trigger happy," he whispered furiously.

He looked at his professor again, who was bare of any tactical weapons or guns except his sword.

"You said you'll come to extract me but you don't even have any weapons except for a fucking sword?!" Charles gave an exasperated cry, still trying to stay quiet.

"Now, now. This is a magical sword, Charles." He sounded condescending and it made Charles' blood boil.

"Shut the fuck up professor. This isn't the time for joking."

Professor Eisner smirked. It was fucking infuriating.

"It's not a joke."

Professor Eisner unsheathed his sword from his waist. The ivory sword—the organic, never-sharpened looking, dull sword—glowed orange. Without an ounce of hesitation, he jumped out from the left side of the tank, exposing himself to bullets from the four Threes who were just five meters away.

"That stupid—" but Charles stopped talking as his jaw dropped.

As the Threes pressed their triggers and released their volley of gunfire, Professor Eisner swung his sword. The sword separated itself into fragments that resembled a spine and moved as fluidly as a whip, blocking the bullets and cutting through them.

A Three who stupidly stopped his firing yelled, "What the fuc—" before the sword, as dull as it was, separated all four men's torso from their legs. Their dismembered bodies plopped down to the ground.

Professor Eisner grabbed one of the Three's gun and shot them each on their head. He dropped it on the ground after and turned to him.

"For good measure," he shrugged.

.

Charles looked at the cadet standing at attention in front of him. He himself had long since graduated from the Academy, so it had been a while since he had seen the scratchy, starched uniforms.

The cadet brought his knee to the ground and his arm formed a salute over his chest.

"This is Bismarck Waldstein, Charles." Professor Eisner smirked. "One of the best that I have ever had."

The cadet bowed his head.

"I don't deserve such praise from the professor but live to serve, Your Highness."

.

The Ashen Demon of Britannia.

It was a familiar name—one that Byleth was called several times before in his life. During the 91st emperor's reign, he was called the Green Haired Demon but would be content with just the title of _Demon_ because _she_ would no doubt recognize it.

His sword, without even a sharp edge, cut through metal, flesh, and bones all too easily. Unlike when he first wielded it against his enemies in Fodlan, the Sword of the Creator vibrated with a different power.

But the new power didn't matter as he shoved the Sword into his heart once again.

_Again._

He pulled the sword out and the wound healed.

_Again._

He plunged the sword back into his chest.

_Again._

He pulled the blade out.

He just wished the blade through his heart hurt even just a little bit.

.

"I'm going on leave, Charles."

It wasn't a request. Professor Byleth was merely letting him know about his leave of absence.

Charles didn't look up from his paperwork. "A leave? For how long?"

"About a year."

Charles' hand stopped moving and he looked up from his forms to give a dubious look at his professor.

"A year? Professor, do you even have enough leave hours accumulated for that?"

Byleth shrugged. "I haven't taken a vacation in ten years. I think I have enough."

It was true that the past seven years that he has known his professor, he hasn't taken a vacation.

"I think that's bending the rules a little. Not that it matters. What about our plan?"

"I wouldn't have come to you if I knew it would interfere in our plan." Byleth gave a small grin. "You know as well as I that nothing dramatic would happen that you cannot fix."

"That is very true..." Charles gave an impassive stare to the professor while propping his chin on his hand. "Well, I hope you enjoy it, professor. Any plans?"

"Not exactly. I'm trying to find someone."

"And what about your lover?"

"I'm talking about her."

Charles' chin slipped from his hand.

"Professor, have you not seen her in the past ten years?" Charles gave an exasperated sigh. "Will she even want to see you? She might have moved on."

"Maybe, but I have to explain myself to her."

"Explaining yourself won't do much. Trust me. I have three wives. And I'm getting married _again_ in two months."

Byleth chuckled.

"I don't have to come to another one, do I?"

"No," Charles almost growled. "Enjoy your vacation."

"Thank you. I'll see you next summer."

.

"Professor. It's good to see you back."

"Thank you, Charles. It has been a meaningful trip."

"Meaningful? Where did you go? Did you find your ex-lover?"

"I went to Europea United. As for her… unfortunately, I couldn't find her."

"To see the day that the infallible Professor Byleth would fail at something," Charles smirked and started to walk away but he suddenly turned back to face Byleth. He scrutinized the Professor's face.

"Are those dark circles I see, professor? Here I was, thinking that you never got tired or old!"

Byleth gave a hesitant laugh.

.

Earlier that morning, Byleth got out the light brown eyeliner he bought in the Chinese Federation and looked in the mirror.

He hoped his skills improved compared to the last time he tried this.

.

It didn't. He just looked like a raccoon.

.

Byleth knew something was wrong even before he opened his eyes to his surroundings. He could feel the binds around his arms and legs.

"Professor."

Charles' hard, impassive face stared straight into him. Byleth stared back, but he noticed from the corners of his eye that he was in the 2nd interrogation room. One that he himself used often as an interrogator.

Byleth furrows his brows but didn't say anything. He _could_ use his divine pulse… but it wasn't as if Charles could actually kill him. He would wait for Charles to move first.

"You're not saying anything… so let me ask you this," Charles gripped his hands together and leaned forward. "Do you have a Code?"

"A Code? I don't have a Code."

Charles's lips curled into a deep frown.

"Profe—"

Byleth felt the bullet go through his head before he heard the glass of the two-way mirror shatter.

Charles rose from his chair so quickly that his chair clattered to the floor.

Byleth felt his body instinctively shutting down, mending itself, leaving just his hearing intact. Oh good, the bullet went straight through. Small blessings that it wasn't stuck inside his brain.

"What the _fuck_ was that for, brother? What if he doesn't actually have a Code? He was useful even without the Code!"

"Charles," a childlike voice rang out from behind the glass. Byleth's brain didn't heal enough for him to lift his head and see who the speaker was though. "He wears makeup to draw wrinkles, nor does he show any signs of aging. If he didn't have a Code, then he is useless.

"Brother…" Charles growled.

"Just wait."

"Ugh," Byleth groaned. "Didn't know you cared so much Charles." His brain _finally_ mended. He hasn't died in a little while, but his healing was as quick.

"So, you _do_ have a Code." Charles eyes grew a bit wide.

"As expected," the voice behind the cracked glass said. Byleth could sense the voice's owner walking toward the door. Soon, a small child stepped out behind the monitoring door. "As I said, Charles—he has a Code."

"I _don't_ have a Code."

From his standing position, the prince banged his hand on the table in front of him. "You just survived that bullet! You recognized what the Code was too! You _must_ have a Code."

Byleth rolled his eyes. "Is your trust in my words so shallow? Search my body. I don't have a Code."

Charles narrowed his eyes at the demon. "We will check later. But if you say that you don't have the Code, how did you survive the bullet? Do you have a Geass?"

"I'm immortal," Byleth tried to shrug but his arms were to tightly bound to the chair. "And no, I don't have a Geass." He turned his eyes to the child. "I'm guessing that you have a Code though, boy?"

"Such insolence!" The child frowned and furrowed his brows.

Byleth laughed. "Insolence? I have been living for almost nine hundred years. You two are _infants_ before my eyes."

"How did you gain your immortality?" The prince ignored the professor's mocking. "How do you know what a Code is?"

"You know, this isn't a very good interrogation. You should get someone else to do it."

"Even if you are immortal, we could bury your body in cement and leave you for a couple of days. I'm sure that sounds _fun._ "

"Charles, oh Charles" Byleth had to chuckle at the prince's threat. "I could be free of these binds already. Also, is it wise to threaten a person who is helping you altruistically?"

Charles snorted. "Altruistic? I get the sense that you are just helping me because of _boredom_ , professor," he spat.

"That is very true… Very perceptive." Byleth would clap with noticeably faux excitement if his arms weren't bound. "I haven't met anyone that approached me knowing about the Code. For that, I'll tell you this. I was cursed by a goddess and thus I am immortal. My lover, who I have been looking for the last 250 years, has a Code. I don't exactly know the details of the Code other than granting someone a Geass and immortality, but do you know of Ce—C.C?"

Charles paused and looked like he was thinking.

"We don't professor, but because my older brother, Victor, has a Code, we may be able to help you find your lover… C.C?" Charles rolled the name off his tongue as if he was saying testing out the name.

Byleth cocked his brow. "You will?"

.

Byleth soon put on a black mask to hide his aging. Or lack thereof.

He just said that he had major burns after his last trip, and people left it at that.

It wasn't his fault that he wasn't aging and had to hide his face. Charles just took _so long_ to get to the throne. Byleth wasn't going to do _everything_ himself.

.

Byleth observed the students duel from the balcony of the fencing club room like a hawk. Its spacious room was and gaudily decorated with glass chandeliers and it twinkled as light it caught the light reflected from metal swords. The whole room was filled with the sound of metal swords clashing against each other.

He stared in particular at the two students who were slashing their sabers gracefully against each other. Marianne Lamperouge, his most current target, and Brandon Ashford, the puppy who always followed Lamperouge around, were very skilled indeed.

Marianne Lamperouge—she was a gem that he hadn't seen since Bismark. She may be even _better_ than Bismark.

For all her grace, Byleth could tell that she had a vicious side as she lunged and slashed at Ashford's weak spot to make him fall onto his back. Flustered at her friend's fall, she dropped her sword. Lamperouge put her hand out for Ashford to take, which he did gratefully. After she helped him up, she took off her mask and helm and let her black ponytail drop gracefully. She gave a small apologetic smile, which Ashford returned with a blush as he too took off his helm. He didn't let go of the woman's hand but instead gave a sheepish grin instead.

Ah, young love.

.

Byleth didn't trust the metal contraptions that Marianne rides with ease. Maybe it's his old age, his natural inclination to use a handheld weapon, or just plain skepticism that makes him choose to ride atop a tank rather than the metal warrior.

Marianne was always ambitious and full of curiosity. It didn't make him feel any better as he let this young 19-year-old girl lead a squadron of men and women from the 1st generation Knightmare Frame—the _Ganymede_ —against the 97th Emperor's armies. But at the same time, as Byleth saw Marianne tearing past the army in a flash, he grinned.

Now, if only someone could make a _wyvern_ , he would gladly ride it.

.

Byleth's expression was blank throughout the whole ceremony. In his mind, he could still not understand.

Even as he brought Marianne Lamperouge to Charles as a capable knight, he didn't expect for them to get _married_ right after Charles rose to the throne.

Well, Charles already had six wives, as well as eight children, but he thought Marianne was getting along swimmingly with Brandon Ashford. He thought that the disastrous machines that the Ashfords developed—the _Knightmares—_ because Brandon Ashford was courting her.

But here he was after the wedding procession, enjoying neither food nor alcohol because of his mask. He looked at the various noblemen and women exchanging fake, pleasant greetings.

The eight-year-old second Prince—he remembered his name was Schneizel—tugged on his coat expectantly for another chess match. He refused to socialize with other nobles, but he couldn't refuse this young prince.

The prince would be a formidable match against Claude.

.

"Checkmate."

Schneizel sighed dejectedly. "Professor, it seems no matter how many times I challenge you, I never win."

Byleth looked at the prince who had grown up to be a fine young man. At seventeen, he already had practice commanding armies and fleets.

"Schneizel, I've lived longer than even your father. How could I be called a professor if my students catch up to me so easily?" Byleth smirked underneath his mask.

"Professor Byleth! Please let me play next!" The seven-year-old Lelouch waited patiently through the prince and professor's match, watching each of their moves carefully. He wanted to try his moves against the professor as well.

Byleth nodded and Schneizel gave up his seat for his younger brother.

Watching the boy turn the board in order to play the black side, Byleth noted how much he loved black.

.

Byleth was training in the garden inside Aries Villa, swinging a training sword instead of the Sword of the Creator that was on his hips. He knew that he would be more destructive to his small training area if he were to use that precious sword instead.

"NUNNALLY!"

Byleth heard a boy's scream, and he knew immediately that it was from Lelouch. He ran toward the sound, knowing that it was somewhere close by.

He soon found Lelouch and Nunnally both the pool, one that their mother forbids them to swim in without supervision. Lelouch was trying to swim toward Nunally who drowning. She was struggling to stay afloat and was swallowing copious amounts of water.

Without a thought, he dove into the pool and quickly swam toward Nunnally with only a few strokes. He quickly grabbed Lelouch as well, not willing to let the boy accidentally drown as well.

His mask made it really difficult to breathe as the water got stuck inside the fabric, but it didn't matter as he didn't feel Nunnally breathing.

Lelouch was coughing on the poolside, looking with Nunnally with worry.

"Nunnally! Nunnally!" Lelouch screamed and Byleth dropped his mask.

The young prince gasped. From what his mother said, the professor was supposed to be over 60 years old, yet his face looked like he was only 25.

Byleth started doing chest compressions and gave a quick order to Lelouch to grab his mother.

Lelouch never ran faster in his life.

By the time he came running back with his mother, Nunally was sitting up and coughing out water from her lungs. Professor Byleth was supporting her back and his face mask was back in place.

Marianne ran to Nunnally, who started crying in her arms. Lelouch gave a relieved sigh, and he forgot about not seeing the rumored facial burn underneath the Professor's mask but rather a very young face.

.

Marianne was dead.

Lelouch and Nunnally were exiled to Japan.

Japan was invaded by Britannia.

All in the year he was gone.

Byleth hadn't felt such emptiness in a while.

But he hid it as he looked at Charles, and gave a nice greeting.

A demon was good at not betraying his emotions. It was a long game, but time was always on his side.

.

Byleth was saddened by the death of Clovis, but he never connected with that child (along with hundreds of Charles' other children).

Byleth was impressed at the man who called himself Zero. He was spectacular, to say the least, but Cornelia was sent to take care of him and Byleth knew how capable she was.

Byleth was even sadder when he heard of Euphemia's death than that of Clovis'. Euphy was a sweet and gentle girl. Byleth knew something was wrong—there was no way that Euphemia would suddenly change her mind from helping the Elevens to killing all of them without something supernatural happened. He suspected the Geass.

Byleth was overjoyed when he saw Nunnally for the first time in eight years. It's been so long since he's been so happy like this; it only made him feel even happier when he heard from her that Lelouch was still alive.

But where was Lelouch?

.

Suzaku, freshly knighted as the Knight of Seven, was introduced to men and women all throughout the day. Gino Weinberg made it his personal job to introduce him to basically _every single person_ in Pendragon. The Honorary Britannian was already so tired from giving and getting so many introductions, but he kept his smile up.

"Professor! I'm so glad you are here today!" Gino exclaimed and Suzaku sighed inwardly. Great, another person to talk to.

Suzaku looked at the man who was walking toward them. He had bright, lime green hair that reminded him all too much of the green-haired witch. His nose and mouth were covered by a black mask while his bangs covered up most of his eyes. Suzaku didn't like that a man could just walk around Pendragon masked. He didn't like masks.

"Gino, bothering another fresh knight? I think you should give him some time alone to rest."

"Hahahaha, I think he could use your training more than rest, Prof," Gino laughed. "Oh, Suzaku! This is Professor Byleth Eisner, Knight of Twelve. Prof, this is Suzaku Kururugi, Knight of Seven!"

Suzaku had been introduced to most Knights of the Round already but was not sure what to think about this man. He personally didn't care too much about a Knight who was the last of the Rounds because he needed to become the Knight of One.

"Nice to meet you, Sir Eisner." Suzaku smiled. "Gino called you professor—did you teach Gino?"

"Nice to meet you as well. I do teach Gino, but it is mostly a nickname."

Gino laughed. "Professor Byleth teaches all the Knights of the Round, but the name is mostly because he is was the professor of Emperor Charles and Sir Waldstein when they were students at VMI."

"Oh, wow." Suzaku had some more newfound respect for the professor. Oh wait… did this mean that this professor is older than the Emperor who is 62 years old?

"To be honest, I don't like using last names with the Rounds. Do you mind if I call you Suzaku?"

"Of course not! Would you rather have me call you Professor or Sir Eisner?" Suzaku didn't dare ask if he could use the Knight of Twelve's first name. The man was most likely already seventy years old.

Byleth shrugged. "I suppose Professor is better. But Suzaku, please make some time tomorrow for me. I need to make a training plan for you as you are now one of the Rounds."

"Oh, of course, Professor."

.

The Knight of Seven was convinced that the Professor was actually part Knightmare with how quick and powerful he was. There was no way a 75-year-old man could fight like that.

Once again, Suzaku was back on his butt as the professor's training sword pointed toward him.

"You need to work on tactical variety, Suzaku. Your movements become very easy to predict. We'll work on your footwork and other sword styles for the next three weeks."

Suzaku nodded. "Professor, will you also be making a training plan for piloting Knightmares?"

Byleth shook his head. "I don't pilot Knightmares."

Suzaku's eyes widened. "Oh… uh, then how do you fight in battles Professor?"

The Honorary Britannian mentally hit his head. He sounded so disrespectful. The man probably fought in wars where there were no Knightmares.

Byleth hummed underneath his mask. "Suzaku, get your Knightmare fired up and come back here in fifteen minutes."

Suzaku looked a bit confused but within twelve minutes, he was back at the Rounds training ground.

"Okay now, attack me." He threw the training sword from his hand and took out the white sword from his hip and got ready in a fighting stance. The white sword, Suzaku remembered as he saw it closer up earlier, was dull and cracked.

"What? Professor, you're not in a Knightmare! You will be crushed!" Suzaku yelled through his intercom.

Byleth's eyes glinted. "Suzaku, are you disrespecting my capabilities? Attack me."

The white knight hesitated, "Professor…."

"Suzaku!" The Professor yelled. "I. Said. Attack me!" his voice rang out dangerously.

Suzaku furrowed his eyebrows, but he readied his controls. He just hoped the Professor could jump out of the way, but the twenty meters distance that the Professor had could be closed within a second by the Lancelot.

He charged.

Suzaku wasn't sure how it happened, but within a second, there was something cold against his neck. The Professor who was _right there_ in front of him was gone. Looking up, an ivory sword was protruding from the top of the Frame and aimed toward his neck.

"Looks like I will have to pay Lloyd for the repairs. He'll know who to charge. Also, please remind him that he is two months behind schedule on my project." The professor's voice, a bit muffled by the metal frame, vibrated through the top of the Knightmare.

.

"How is it that Professor Byleth beats me while I'm on my own Knightmare?! How the hell is he so nimble when he's over seventy years old?!" Suzaku covered his face with his two hands while he recounted his embarrassment.

Gino cackled. "It's an unspoken rule, Suzaku, but the Knight of Twelve is the strongest out of all of us. Even when using explosive weapons, the Professor is able to dodge all of it. I don't even want to ask how he does it with his age."

"Why didn't you tell me that yesterday?" Suzaku groaned. "Also, why is he not the Knight of One then?"

"Hmm… we don't really know for sure either, but my own guess is that he didn't want it. Emperor Charles respects the professor immensely. The Eisner family is infamous, you know. The family already helped put three emperors to the throne before and the Prof did the same for Emperor Charles." Gino paused. "Also, you saw the sword on his hip, right?"

Suzaku nodded. "It looks like it is dull but it was able to penetrate the Lancelot."

"It _is_ dull. I don't even know how, but that sword is _mystical_. It can _cut through_ Knightmares. I'm convinced that it is made of something stronger than Sakuradite. Even with his mask on, people can recognize him just from the sword."

"Why does he wear a mask anyway?"

"Apparently, he got a nasty facial burn over thirty years ago. And people told me that he was quite the looker too."

"I see…" Suzaku thought quizzically.

.

Byleth's eyes glinted with childish excitement when he saw the metal contraption.

 _His_ metal contraption.

It wasn't a Knightmare—he still refused to pilot one—but it was a metal _wyvern_ that was capable of flying and _so much more._

Gone were the days that he had to _run_ to evade a missile. Oh no—now he could _fly._

He spent a small fortune (that didn't even put a dent in his wallet) to sponsor Lloyd to make the _Wyvern_ , but it was worth every cent. It took a very long time, but riding atop of one and flying through the sky to cut down some obnoxious Knightmares was _absolutely worth it_.

.

"Professor," Charles looked quite satisfied in his magnificent office chair. "There is something I need to talk to you about."

Byleth quirked his brow.

"I have found your lover—C.C. She was sighted in Area 11, aiding my son Lelouch who is also known as Zero.

Byleth grinned with a murderous glint in his eyes.

"And how long have you known this?"

.

Byleth used six divine pulses—more than he has used in a long while—when Charles told him about C.C.

To be fair, it would only have taken one, but Byleth could not hold his anger at the fact that Charles had used C.C. to manipulate him for the last 40 years and killed him five times just to satiate his anger.

It felt _so good_ to stab the two-faced bastard, but he wasn't completely satisfied.

Byleth always suspected Charles for a long time.

He _knew_ that Charles hid something from him, especially after Charles and Victor took him to the interrogation room. After living for almost a millennia, it was easy to see even the slightest changes in voices and body language, as well as lies. Charles was an infant compared to Byleth's experience. But Byleth waited. The past few decades have been dedicated to making Charles actually believe that he _liked_ Charles.

Byleth never liked the man. The only reason why he ever gave Charles his support was because he saw potential.

And because he was bored.

He never really liked Charles, but now, Byleth _hated_ him.

In ways, Charles _did_ help Byleth find C.C. His support for Charles also led him to Marianne, who Byleth actually cherished, and Charles said that his plan will 'bring her back' when Byleth interrogated him. He didn't believe Charles. He never really did, so certainly not now.

The vi Britannias—Byleth slammed his fist to the wall. Charles abandoned them to die in Area 11 when he chose to invade it. He said that he loved Marianne the most out of all his numerous consorts, yet Charles let Marianne's children be almost killed. Hearing about the Sword of Akasha, the foolish child's beliefs that he can make the god of this world—the Collective Unconsciousness—submit to his will just reminded him darkly of the Agarthans who believed that they could do the same.

But Charles didn't remember Byleth's anger. He just remembered Byleth smiling underneath his mask happily say _thank you for finding her. I'll bring her to introduce to you._

Byleth smiled darkly.

That motherfucker Charles would get what he deserves. Oh and that brat Victor too.

.

When Byleth saw the Ganymede again for the first time in eight years, albeit through a screen atop of an airship, he had to fight the tears that threatened to fall. While he was standing guard next to a blind princess, he couldn't afford to have anyone see him in such a weakened state.

Seeing the Ganymede— _her_ Ganymede—made him remember the times when he tried to grab and consequently rather roughly tossed and turned on top the Ganymede by Marianne.

Now, instead of the blue flash it left as afterimages when Marianne zipped through her enemies, it was regarded as an old antique that was capable of making _pizza_.

Byleth didn't exactly care about the pizza part. But looking at the original Knightmare Frame, he only wished that it was Marianne in the cockpit instead of the young Knight of Seven.

The lovely Marianne, flashing through her enemies and leaving only burning rubble behind.

Nunnally, with gentleness so _painfully_ similar to her mother, grasped onto his hand as reporters talk about the original Knightmare Frame feverishly.

"Professor, did you see my mother piloting the Ganymede before?" she asked with innocent excitement.

Byleth choked.

"Yes… she was the epitome of a goddess."

.

Byleth was unfazed by the unnatural rumbles echoing throughout the airship. He knew that fighting was going on behind the walls, but a 10,000 feet drop wouldn't kill him.

He already tried that once.

But he did have a slight problem. The little princess wouldn't survive the fall, so his _Wyvern_ was already powered up and ready to take flight if needed. Hearing the Britannian comms, it seemed like they needed to leave soon as Zero already infiltrated the ship.

As Zero—Lelouch, he reminded himself—walked into the garden, he didn't know that Byleth would be guarding the princess right next to her. Only four people knew that he would be coming to Britannia with Nunnally. The Demon put a hand around the hilt of his sword. Whatever Lelouch did, he would not be faster than him. But Byleth wouldn't kill him.

"That's you there, Zero, isn't it? Have you come here to kill me as well?" The princess cried out. "Like you did my brother Clovis, and my sister, Euphy?"

The Black Knight's leader paused thirty steps away.

"Even so, will you wait just a moment, please? I think what you are doing is wrong!" The princess said with hesitancy.

After a moment of silence, Zero responded, "It is Britannia that is wrong."

And Nunnally—Nunnally was a strong girl. Her conviction and inner fortitude reminded the Professor of Marianne. She _chose_ to come to Area 11 in order to make things better. She came to make Euphy's dreams come true. And she asked the man that killed her to help that wish come true.

He felt the ship shaking even more.

"No time. We're going now Nunnally."

"Wait, Professor! Zero—" Disregarding her cry, he grabbed her thin body and jumped onto the _Wyvern._ Nunnally gave a terrified scream, but the _Wyvern_ grabbed onto Nunnally's wheelchair with its claws and he used a missile from the metal dragon to blast a hole to get outside of the ship.

"Sorry Nunnally, but this old man isn't going to let you die anytime soon!" He glanced at Zero flying through the air but getting caught by one of the Black Knight Knightmares. "I don't think Zero is going to die anytime soon either."

.

Byleth looked at the news about the Black Knights and the Chinese Federation with minimal interest. Schneizel is a smart boy, but the prince still had long ways to go if he wanted to completely overwhelm his younger brother.

"Sir Eisner! Thank you for waiting!" A joyous voice rang out and Byleth looked up from the waiting room chair.

"It was no problem, Mr. Ashford. I hope everything was in order?"

"Yes! I can't believe that you are Professor Eisner's son! He actually taught my son as well! It's great to see you following in your father's footsteps." Ruben Ashford exclaimed loudly.

"Yes, he told me about your development of the first Knightmare Frames. He holds great respect for you and your son."

"I'm happy to hear that!" The Academy Director's eyes gleamed. "I hope this is not too forward, but why did you choose to teach at this Academy? Not that I don't mind, but you are overqualified for this job! Not to mention, you are the heir apparent to the Duke of Fodlan."

"Ah, well you see, my father needed to have _someone_ watch over his past students—the Knights of the Round," he smiled.

.

Lelouch hadn't come to class yesterday as Rolo turned off his alarm and made Lelouch sleep in for four hours so he missed most of his classes. It was nice to relax though, as he _really_ needed the rest.

He greeted some of the students that said hello to him down the hallway and many girls giggled back in response.

The doors to his classroom opened automatically and he saw Shirley and other girls, giving them a fake smile and a hello.

As he took his seat, he heard some whisperings, but it wasn't the normal whispering that was mainly about him. He nonchalantly pretended to be absorbed in his textbook while he opened his ears to the gossip.

 _"The first class is Mr. Jeralt's class. I'm so excited!"_ one of the girls squealed.

_"He's a knight, right? So we can call him Sir Jeralt, right?"_

_"Why do you even call him by his first name? You should call him Sir Eisner."_

Eisner…?

It was a familiar name. He shook his head inwardly at the distraction. The teacher would be coming soon and he would soon see who it was.

"Mr. Lamperouge?"

Lelouch almost jumped at the voice that called out his name right behind him. He couldn't even sense or hear a person coming behind him.

He turned around slowly as the girls surrounding him in the class began to squeal even louder.

Lelouch stared at the man in front of him.

"…Professor Byleth?"

"Ah, you're talking about my father." The young, green-haired teacher smiled. "I am Jeralt Eisner. Please come to the Guidance Office after school today to talk about your poor attendance."

His classmates whispered.

_"Poor Lulu… but at the same time, I wish I was him!"_

Lelouch disregarded the talking behind him.

"Yes, of course, Mr. Eisner," Lelouch gave an eye smile at the teacher who nodded and walked up to the front of the classroom.

The Black Prince's expression turned somber. He remembered the Knight of Twelve standing next to Nunnally inside the airship. He remembered seeing the Professor so often in Aeries Villa eight years ago. It wasn't on his mind for years due to more important matters—his mother's death, Nunnally's condition, their exile, the invasion—but Lelouch also remembered Professor Byleth's young, bare face.

Jeralt Eisner and Byleth Eisner looked the same.

.

Lelouch wasn't exactly sure if he wanted to go to meet Mr. 'Jeralt' Eisner after his last class today, but he confidently walked down the hallway towards the guidance office. During his lunch break, he accessed the academy's files through his computer and saw the teacher's file.

_Sir Jeralt Eisner_

_Age: 30_

_Gender: Male_

_Date of Birth: September 20, 1987_

_Details:_

**_[Details are secret according to the rule of the Britannia Army]_ **

_Professor of Strategy and Military History, Victoria Military Institute, 2014-2017_

**_-REDACTED-_ **

_Colonel, Britannian Royal Military, 2005-2017, knighted June 2012_

**_-REDACTED-_ **

_Education:_

_Pendragon Military College, Graduated 2012, Ph.D. in Military Science_

_Pendragon Military College, Graduated 2011, Masters in Military Science_

**_-REDACTED-_ **

_Victoria Military Institute, Graduated 2005, Bachelors in Military Science_

Lelouch didn't remember the Professor having a son. Or a wife. Should he confront the teacher about this or wait till he revealed something? As a person who always black in chess, Lelouch determined that he wouldn't make a decision until the teacher played his cards.

He opened the door.

"Good, you're here." The teacher was standing in front of the table, his arm dropping from the thinking pose to his side. Lelouch scanned the green-haired teacher. He was wearing the _exact same uniform_ as the Professor, Knight of Twelve. Along with his ivory sword.

"Your uniform… Are we not doing counseling?"

"No, we're not. C.C is at the Black Knight's base, right? Now take me to her."

The prince spluttered. Was this teacher/professor(?) tasked to find C.C. by the emperor? He made up his mind quickly. He reached for the contact lens.

"I, Lelouch vi Britannia, command you—obey me!"

The teacher looked impassively for a second.

"So that's your Geass?"

The prince's eyes widened.

"Brother!" Rolo's voice rang out behind him and Lelouch saw that the Professor was inside Rolo's time stopping sphere. "I knew his files were suspicious. Escape now!"

But the professor walked toward them, seemingly unaffected by the Geass.

Disregarding the shock, Rolo took out the gun and shot at the man. The prince's mind rang with the implication for this man's immunity to the Geass and the implications for _shooting_ the teacher if he wasn't what Lelouch suspected to be.

The teacher stopped after getting shot. And crossed his arms.

"As I've said, Lelouch, take me to C.C."

Rolo lowered his gun, knowing that it was futile after realizing what the man was.

Lelouch was also sure of it now. "So you _are_ Professor Byleth?" Now, the professor's incongruous young face from his memories made sense.

"Yes, normally I wouldn't be so hasty or demanding, but I'm an anxious man. I need to see C.C. _right now, i_ f you would be _so kind_ to lead the way _._ "

The professor gave a terrifying smile.

.

C.C. didn't even look up as the doors opened. The only person it would open for automatically would be for Lelouch anyways. She had Cheese-kun comfortably inside her arms while she was reading a novel that wasn't half bad.

"You're here earlier than you said. Get me some pizza, boy."

"Cera."

The Witch stopped turning the page. She refused to look toward the sound. Her hands shook.

She was afraid—afraid that her past caught up to her.

The speaker moved inside the room, and the door closed but C.C. still refused to look up.

"Cera."

The speaker kneeled on one knee in front of her and his face was a foot away. C.C. finally looked up and saw the unchanged face of her former lover gazing at her with a relieved smile.

"I've missed you."

* * *

_A.T.B. 1468_

She was strapped to a burning stake again.

Tears streamed out of her eyes as she saw the young man that she trusted— _loved—_ jeer at her along with all the other villagers she lived with for three years. Why was it… why was it that whenever she loved or trusted, they, in turn, could never do so? Her former lover's left eye swirled with his Geass. Was it to mock her? She didn't quite know but she just wished that he would have unlocked the full power of the Geass to put her out of her misery.

She trusted once again, only for her to get betrayed.

It hurt. As the flames touched her bare feet, she cried out in pain. But more than the flames, the betrayal and jeers hurt even more.

She bit her bottom lip to conceal another cry, but it would not be far until she would start screaming. The flames reached her calves and she could feel blisters and burns consuming her legs and feet.

C.C. closed her eyes, just hoping this would be over quickly. Hopefully, they put more firewood because then it would end more quickly. With her eyes closed, she heard the chanting of 'burn the witch' along with other names the overzealous townspeople wanted to throw at her. Her only solace was that they would think that she was dead. After her death, her ashen remains will be thrown into the woods, where she could replace her lost body parts from C's World. She would then roam again until a village accepted her and she vowed _this time_ she would not trust nor fall in love.

But from the shouting, she also heard a loud cry—from a horse?

_Was that a horse neighing?_

She opened her eyes and instead of the townspeople, she was greeted by a green-haired man jumping from his horse toward her.

_What?_

With one swing of a dagger, he freed her from the binds and grabbed her as he jumped back on his horse before any flames could burn him. With a crack on his reins, he trampled a few villagers and stole her out of the village.

.

They finally stopped, giving her time to speak her mind.

"Why did you save me?"

The green-haired man—his hair all too similar to her own hair color—gave a small grin.

"It didn't seem fitting to try and court a lady while she was being burned alive."

She stared at the man incredulously. "Do you know why I was being burned alive? They say I'm a witch, _boy_."

"Boy?" The man laughed. "I haven't heard that before." He hummed and handed her a water flask to which she grabbed greedily. "So _are_ you a witch?"

She didn't respond but instead pointed to her legs. C.C. knew that he saw the burns earlier. She used the time to escape from the town on the horse to heal her feet. She considered leaving some burns if the man had any questions, but C.C. supposed that she would just kill herself if he tried to do anything. The man would have to abandon her in the woods.

The blisters and burns hurt too much to just leave alone.

"Do you have any problems with a witch?" She flipped her long green hair slightly nervous of the man's actual intentions.

The man laughed once again.

"If those people call you a witch, then I would be called… _a_ _demon_."

.

Maybe, she'll trust. Just one more time.

* * *

_A.T.B. 1473_

Sometimes, they acted like siblings; sometimes they acted like lovers. Their matching hair colors made many heads turn no matter what persona they put on. They didn't really have a goal or a purpose in their travels, but it was thrilling enough.

After their pleasant night together, C.C. finally asked. "Byleth… do you… have a Code?"

With eyes filled with genuine curiosity, Byleth replied, "What is a Code?"

C.C. narrowed her eyes and lifted Byleth's arms, made him turn around, and kept searching Byleth's bare body while he laughed from her soft touches.

"Is this a new sensual game, Cera?" Byleth returned her sensual touches with his own and loomed over her to give a passionate kiss.

C.C. broke the kiss and huffed. She had seen her lover's bare body countless times by now, and like ever, there was no new tattoo or symbol that looked like the Geass. She flipped him over his back using the moment. Unfortunately, no symbol on his bare arse either. Now _that_ would be hilarious.

Furthermore, weren't there any scars or injuries.

"How did you heal from the bandit's dagger so quickly? Also, how do you not age?" she accused.

Byleth shrugged. "You don't either, Miss Witch. But, to answer your question, I _think_ I'm immortal."

"You think?" C.C. asked with an indignant cry. "What do you mean _you think_?!"

"I never really wanted to find out if I only never aged or if I was immortal."

"Is that even possible?"

"My father didn't age… but he was able to be killed." Byleth softly grasped a lock of C.C.'s hair and twirled it between his fingers. "By a dagger, no less." He sadly snorted.

"Oh…" But C.C.'s furrowed eyebrows suddenly turned up into a smirk. "You had a father? Here I was, thinking that we might have been committing some sacrilegious incest." She flipped her hair, making Byleth make a small whine as C.C.'s lock of hair escaped his fingers.

"I don't believe I had any siblings. Not that I really care about the laws and rules from the religion here."

C.C. smirked and laid her head on top of Byleth's chest. "Neither do I, but I figured as you didn't enjoy the chapels very much. When were you born?"

"I think about four hundred years ago."

C.C. lifted herself up stared at her lover. "Four hundred years? How did you not die or boredom? How did you not die at least once?" It had only been about sixty years since she had received her Code. She couldn't imagine living so long without it getting boring, because _she_ felt bored before meeting Byleth.

Byleth slinked down into the sheets.

"I spent it mostly exploring. As for not dying, I have an ability to helps me a bit." Byleth winked. "I'll show you sometime."

"My, my. So many mysteries." She flopped down on the bed next to Byleth with an exasperated sigh. She propped her chin on top of her hands. "Do I really need each and every question for you to give me an answer?"

"If not, how will we last the next millennia without boring each other?"

C.C. smiled. She wouldn't mind that too much.

* * *

_A.T.B. 1528_

"Why do you even like this scented water?" C.C said as she spat back the drink back into her drinking cup.

Byleth looked a bit affronted.

"It's not _scented_. It has an _aromatic_ taste!"

C.C. rolled her eyes.

"We just spent half of the money we had for a tiny bag that weighs less than a pound. And it's not even food."

"Tea isn't just for drinking." Byleth took another sip. "It's also to spend time and talk with people. Anyways, I haven't drank tea in centuries!"

"And yet you berate me for buying too much cheese," she said as she rolled her eyes.

* * *

_A.T.B. 1604_

C.C. cried in front of their seventh adopted child's grave.

Like all the children before him, Corin never reached the age of twenty before dying.

"Cera… I'm sorry, but it was fated."

C.C. turned around abruptly, giving a ferocious glare to Byleth. "Fated?! What do you mean fated?! I can't believe you! You can save your own life but cannot save our child's? How could you say that it was fate?!"

Byleth couldn't respond back, because it was true.

* * *

_A.T.B. 1647_

Byleth held his breath. If he was a more emotional person, tears would be flowing out in streams.

"So you were born here? There's… nothing left," C.C. said sadly.

The ruins of Garreg Mach was overrun with greenery and trees atop once impressive towers and buildings.

"Yes… it was destroyed hundreds of years ago. When it did, the land surrounding the monastery fell to the sea. A continent was reduced to an island. And my students were… all buried underneath this rubble. Over there—" he pointed at rocks overrun by green moss. "That's where we were, celebrating the end of a war. But then I felt this sudden, unbearable pain. And then I woke up and was floating in the middle of the sea."

C.C. looked around. She could imagine the grand Monastery that once stood on these grounds. But now, the signs of the buildings and life were all worn down and covered by wildlife.

"How long has it been since you came back?"

"About 600 years? I didn't visit even once. I couldn't. The guilt of being the only person alive when every one of my students was dead made me so… _scared_. But with you, I could finally come back." Byleth gave her a big, genuine smile. "Thank you Cera."

C.C. returned the smile. "Byleth, thank you for bringing me here."

Byleth swooped down to give her a kiss.

_"Byleth... Byleth."_

Byleth stopped.

"S-Sothis?" He turned and looked around. "Where are you?! Sothis!"

"Byleth? What are you saying? Who is Sothis?" C.C asked.

"She's somewhere around here! I can hear her!" Byleth ran to a hill of rubbles.

C.C. chased after him. "Byleth! Where are you going? I can't hear anyone except for us!"

She was breathless by the same time she caught up to him on top of a tall stone staircase. He stopped in front of a stone chair that was untouched by the infestation of plants. While it was surrounded by rubble, it stood magnificently, glowing iridescent green. The back was at least ten meters long and a large oval swirl design decorated the middle of the backrest.

"Where are you, Sothis!" he cried out.

"Byleth." C.C. had a painful look on her face. "Who is Sothis?" She already knew the answer.

Byleth bit his lip.

"She was… my first love."

* * *

_A.T.B. 1688_

C.C screamed at the severed body in front of her.

"Why… _why_ did you kill him?!"

"He hurt you while he had the power to kill you now! I can't let such a person survive!"

"Byleth, the axe was an accident! And he didn't even _know_ that he could. How could you do such a thing… when he was like our own _child_?!"

"Cera," Byleth responded grimly. " _Nothing_ is more important to me than you. Not even our adopted children. I will _never_ let you die."

 _But what if she_ wanted _to die?_

* * *

_A.T.B. 1702_

C.C. gave a sad smile as she saw her lover finally hoisted his flag of Garreg Mach over his homeland—the continent that had been reduced to an island. The Emperor that they put on the throne was very receptive to giving Byleth the claim to the island and the surrounding lands (not that the emperor could even refuse).

Fodlan was a mystical island: always covered by fog and never explored except for the shores for cartographers to map. For one reason or another, the cartographers could never go past the shores and were limited to mapping the surroundings only.

It didn't really matter as Byleth didn't plan on letting people intrude onto his precious homeland.

He planned to build a house for them to live together. He planned to explore after a few and find children to foster in the land. He planned so many things, but C.C. didn't plan the same.

She boarded the sole boat to the island that night and left alone.

* * *

"I've failed you in so many ways, Cera."

C.C. didn't respond, but her silence said volumes.

"I've had three hundred years to think. Because I lived for so long... I forgot what it really means to be a human—what it means to have just one life and always afraid of dying."

C.C. didn't respond again.

"I need to explain how I got my immortality. This sword…" He took the Sword of the Creator out of his belt. "It's made from the bones of Sothis."

That finally made her expression change. "The bones of your first lover?" C.C. asked with a disturbed look on her face.

"Yes…" He nodded. "She died almost a thousand years before I was born. She was a goddess—"

"Stop. Whatever you're trying to convince me with, it's not working Byleth," she sighed.

"No, no, Cera. It's not a metaphor. She was an actual _goddess_. She came to my world, or I guess it was just a continent, about a thousand years before I was born. She helped a group of humans called Agarthans, but they betrayed her and killed almost all of her descendants, which made her sacrifice her body in order to defeat these Agarthans. Her daughter stored her heart in human containers and tried many experiments to revive her mother. One of the containers over the years was my mother. My father received the blood of the goddess' daughter, which made him unable to age. The goddess' blood from my father, added with the goddess' heart transplanted from my mother to me, caused the goddess' cognition to be developed within me. She lived within my mind and it was due to this that I am able to use this sword that was made with her bones."

The goddess' heart doesn't beat, but it does when I use a Divine Pulse, where I am able to turn back time to a certain extent. Even with this power, I couldn't save my father who _died right in front of me_.

Sothis taught me, that when I turned back time and couldn't save him, it was fated. Whenever our children died, I used it to the maximum amount of times to find a way to make them live. Sometimes I could save them, but in the end, none of them could survive past their fate.

When I couldn't save my students all those hundred years ago and when I couldn't save our children, I stopped caring about humans because if I did, then I would be hurt again. Yet I keep making the same mistakes. Marianne… she was like a daughter to me. She was so _powerful_ and full of _life_. I thought that she would live until she got old. But I couldn't even save her."

Byleth gave a strained laugh and looked toward her again.

"Cera. Sothis cursed me with this immortality and I hated her for it, but at that time, I needed to ask her _why. Why_ I was the only one that lived that day. _Why_ I was cursed with this immortality. I loved her and then hated her for so many years." Byleth paused. "But I am thankful to her—because I met you. I only truly lived the past five hundred years because I loved _you_."

"I asked you all those years ago… Why did you not tell me earlier and only tell me now? We can't go back to that time." C.C.'s brows scrunched up and she pushed him away.

"Please, Cera. Please." Byleth went on both his knees. "There's nothing for me but you. I don't have anyone left except for you. I don't even _know_ how to die. I've tried killing myself, so many times, in every possible way but I couldn't die."

Byleth never died even once in the two hundred years she had known her. Nor the four hundred years he roamed the world alone.

"I don't care if you don't love me. You could hate me. You could leave again and but please," Tears streamed down from his eyes. "Please don't kill yourself."

.

Suzaku didn't really believe in coincidences anymore. Not when the Geass can artificially create such coincidences.

When the green-haired teacher introduced himself as Jeralt Eisner, son of Byleth Eisner Knight of Twelve, Suzaku wasn't as excited as Gino who asked all kinds of invasive questions to the teacher.

He couldn't quite explain it, but something was not right.

The teacher's all too familiar voice. The teacher's all too familiar way of teaching. It was too similar to the Professor. Even if they were father and son, it didn't exactly explain how Gino didn't even know about him—the annoying blond knew _everyone._

Byleth saw the Knight of Seven's suspicious glances. The boy was not a good actor. He was also too truthful to be an actor.

"Mr. Eisner…" the brunette knight started. "I haven't seen the Professor since the viceroy's inauguration. Do you know where your father is currently?"

The teacher hummed. "I believe he is somewhere else in Area 11 for a special mission, I haven't seen him in a while either though, Sir Kururugi. He said something about a witch?" he said nonchalantly.

Suzaku's breath hitched. Ah, so the boy knew about Geass and Cera. Byleth wasn't sure of Suzaku's mission by the Emperor because it didn't come up during his _interrogation,_ but it must have something to do with Zero—Lelouch. The demon glanced over the Honorary Britannian's shoulder to stare at the Black Prince who in turn glared back at him.

"Oh, and speaking of my father… he told me that you were a talented knight… _strong enough to become the Knight of One_ ," the Demon smirked.

The boy narrowed his eyes.

.

Byleth looked at the destroyed area that was once called Tokyo. The settlement was now just a gigantic basin due to the FLEJA and Byleth cared.

He might not be human anymore but he still cared.

.

Byleth looked rightfully enraged.

"What have you done to her? I should kill you now… " The Demon held his sword to Lelouch's neck. "I've killed many of her contractors for far less," he growled dangerously.

C.C. trembled as she hid behind Lelouch.

"Professor, please, I didn't do anything! After I confronted my father and C.C. chose to not die for the Ragnarok, she suddenly lost all her memories!"

The professor's eyes turned from anger to shock.

"So… she chose to live instead of dying?" He dropped his sword. "What _have_ you done to her?"

.

"Are you here to stop me, Professor?" Suzaku brandished his sword against the Ashen Demon.

Schneizel didn't expect the confrontation in front of him. He looked at the Professor, hiding his worries. Professor Byleth was the one instrumental for his father's ascension to the throne. He was _unbelievably_ strong. Although the White Prince had faith that the Knight of Seven would be able to kill his father, he was doubtful that _anyone_ could defeat the Professor. Also, the Knight of Three, who was hesitant about who to give his loyalty to currently, would gladly assist the Professor if he asked.

Would the professor kill Sir Kururugi and kill everyone else in the room who dared to say such traitorous things? The Professor was such an enigma that Schneizel could not predict his actions.

The Demon laughed. "Oh Suzaku, not that you can ever beat me, but what makes you think I'm trying to stop you?" His eyes glinted dangerously. "I'm going with you to kill that motherfucker once and for all."

.

"Professor…" Charles narrowed his eyes. "Why are you here?"

"Charles, you thought that you could fool me for forty years and think that I'll forgive you because I helped you get the throne?" His face was smiling but his eyes told a different story. "No one," he glared at Marianne. "Not even someone I considered a _daughter_ is more important to me than C.C."

"It's meaningless, professor. You cannot even kill me. I am immortal." Charles laughed.

Byleth hummed. "What was it that you said to me all those years ago? Oh, yes. _Even if you are immortal, we could bury your body in cement and leave you for a couple of days. I'm sure that sounds fun._ I think it'll be even _more_ fun if I leave you there for eternity!" Byleth gave a sadistic grin.

"Professor," the Black Prince stopped him. "Please, let me be the one to get rid of this _scum_ called my father. And the _heartless_ woman called my mother."

Byleth quirked his brow, gave a mock bow, and conceded.

.

The Sword of Akasha was collapsing on itself.

"It seems that you didn't even need my help becoming the Emperor. Congratulations Lelouch." Byleth sounded mildly amused. He turned around, ready to leave the crumbling world.

Lelouch smirked. "I could use your help to take the throne though, Professor."

"Not yet. Our talk isn't over yet, Lelouch," Suzaku narrowed his eyes and Lelouch gave an affirmative nod.

"Oh did I ever tell you, I actually killed Charles five times by turning back time because he tried to fucking manipulate me? That piece of shit." Byleth cackled.

C.C. sighed. "It seems that you have gotten crass since I've left. Whatever. Let's go now. C's World can be depressing if you stay too long."

With a nod, the quartet stepped down the stairs to leave.

 _"Byleth,"_ a soft voice cried out.

Byleth stopped and turned his head to the voice.

"…Sothis?"

 _"Byleth. It's been so long since I was able to talk to you."_ A young girl with long, dark green hair wearing a flowing dress floated down in front of Byleth. _"We can finally talk."_ The girl looked so happy but the Professor didn't share the same sentiment.

"Sothis… Why are you here?" His eyes turned murderous.

_"I couldn't talk to you before because—"_

"How could you show up _now_!" Byleth's voice was drenched with rage "You've left me for eight hundred years—cursing me with this immortality that I never wanted. When Fodlan was destroyed, why couldn't you let me die with everyone else? Do you know the _guilt_ I felt every single day because of it?"

 _"I am so, so sorry Byleth. But…"_ The goddess bit her lip. " _how could I let you die when I had the power to keep you alive? I know that guilt very well. Of course I know it. I saved you, but never any of my children!"_ Her expression looked so angry and sad.

"Why _did_ you save me? Why can I not die? I tried tearing our your heart so many times, yet I could not die." Byleth gripped his chest. " _Burning, tearing, stabbing, poisoning, drowning_ —I tried _everything_. Why doesn't it even hurt? If I felt the pain, it would have at least numbed my mind."

_"Byleth, why do you think it is that you have never felt the pain? I live within your heart. Every time you kill yourself, every time you get physically hurt, I felt that pain for you."_

Byleth gasped. "Why… why would you _do_ that?! The pain… That must have hurt you so much…"

_"I took your pain for you because you already suffered so much pain that I've caused. I didn't mean to give you a life that you see as a curse. I didn't mean for immortality to leave you alone and isolated in this world. But when you met C.C, you finally had a purpose—something to live for. When she disappeared, I knew that you would be able to find her, so I couldn't let you die."_

"Then, you have chosen for me to live this cursed life? How could you choose such a thing for me? I _want_ to die."

_"But you still have a purpose in life. Just like how you are my purpose in life."_

Byleth's eyes widened.

"Oh… oh… I can't believe… ah… what a hypocrite I am… your love for me—the way you wish me to live—it's the same as how I wish for C.C. to live… how can I ask for her to live if I myself wish to die?" Byleth clawed at his hair at its roots. "Can I even ask her to continue living when I don't want to live either?."

 _"I will let you pass with her when she does. If you still wish for it. Now go."_ She disappeared with a smile on her face.

Byleth nodded.

"Thank you… Sothis…"

.

"You changed your mind."

"I did." The witch responded.

"Because you love Lelouch?"

Her silence affirmed his question.

"I already made a decision already years ago. Even if you didn't love me anymore, I will still help you accomplish anything it is that you want. Even serving Lelouch for eternity if you are by his side." Byleth grinned, but his heart ached.

.

Byleth had just a sliver of hope when he heard of the Zero Requiem plan.

He didn't voice his hope; he would follow the child Emperor's orders to the T.

But one can still hope that C.C. would come back to him if Lelouch died.

.

Lelouch sat on the throne confidently.

When he was attacked by soldiers loyal to the previous emperor, Suzaku took care of them while he himself took care of the nobles.

Professor Byleth took care of anyone who wasn't enraptured by his Geass with just his new name—Jeralt Eisner, Knight of One. Pendragon and Britannia knew what it meant for a prince to be supported by an Eisner.

The Black Prince was the new Emperor.

.

"Professor, do you mind if I take a look at your sword?" The Knight of Zero asked in one training session.

Byleth nodded his head. "Sure."

"So how does this even work? I know you said your homeland was mystical, but how can it cut through metal so easily?" he held the blade carefully and it rattled in his hands

"It's not a normal sword even in my homeland. It's made out of Sothis' bones. Specifically her spine."

"The bones… of your previous lover?!" Suzaku's horrified expression grew even more pronounced as the professor nodded his head in confirmation.

With a yelp, the Knight of Zero tossed the blade up and it almost fell to the ground but the Professor caught it in time.

The Professor glared and hugged the blade dearly against his chest.

"Uhhh… I'm so sorry… I'll never ask to hold that sword ever again."

.

Jeremiah Gottwald remembered the Professor from his duties at Aries Palace. Somehow, his young face and casual display of immortality didn't surprise the Orange Knight.

"So what will you do after the plan?" the green-haired Professor asked.

Jeremiah thought for a second. "I think I'll start an orange farm. How about you Professor?"

A pause.

"I'll guard C.C. as long as she's alive."

The Orange Knight narrowed his eyes.

"And if the Emperor lives? Will that protection also extend to him?"

Byleth didn't want to think about that.

"If I need to, yes. But if C.C. ever feels like she doesn't love the boy anymore, I will be the first one to kill him."

Jeremiah's emotions raged at the Professor's hatred for his Emperor, but he calmed down. The immortal spent three hundred years trying to find his lover, only for her to love another man.

Any sane man would leave and find something new to pursue, but demons were quite possessive and stubborn.

"If you harm the Emperor, I will fight you whether or not you are immortal."

Byleth gave a small smile.

"I truly hope that you will be alive when that happens."

Jeremiah didn't respond, but he understood the Professor's wish.

.

Byleth was disappointed at Schneizel's excessive way of making peace through his FLEJA bombs.

"So... your son sided with Lelouch instead of me. I thought you liked me the most out of all of my father's children, Professor, but I guess I was wrong." Schneizel sighed in defeat. "It would have been helpful to have you and your son—if he really is a _son_ , to help me create a world of peace."

"Schneizel, you _are_ my favorite out of Charles' children. You already figured it out though, haven't you? You would have made a fine emperor…"

The Demon dropped his mask, revealing his bare face to Schneizel for the first time.

"But my lover chose Lelouch. I spent three hundred years trying to find her, and in those three hundred years, I put four emperors to the throne. If I find her supporting a man who wants to be the emperor, how can I refuse her?"

,

"So… he's dead?"

C.C. nodded.

"But I'm going to bring him back to life." She clutched the bloody body of her contractor even more tightly.

Her eyes said _stop me if you can._

Byleth gave a saddened smile.

"I won't stop you. I said I'll serve him for eternity if you are by his side already."

His eyes said _I will still love you._

.

Byleth wasn't sure if his purpose in life was worth watching the woman he loved love someone else.

He finally understood what Sothis felt.

He pleaded— _let me feel the pain._

He stabbed his chest with the Sword of the Creator.

It hurt. The pain was excruciating, but it numbed his mind.

He pulled the Sword out.

_Again._

**Author's Note:**

> I hate Charles zi Britannia. Seriously that man is an asshole.  
> I feel bad that Byleth gets such a bad ending... but he finally realizes that this is exactly what Sothis feels when Byleth loves C.C. Poor Byleth :(


End file.
